Optical conductors are in common use in the field of telecommunications. Data is generally conveyed optically at a wavelength of approximately 1300 nanometers or 1550 nanometers by optical fibers based on silica. Each fiber is protected by layers of a polymer material, and the protective layers are often covered with some other, pigmented, polymer.
A set of optical fibers can be assembled to form a ribbon. In which case, the material of the ribbon is also a polymer.
The individual optical fibers or the ribbon of optical fibers are disposed in a metal tube or in a plastics tube.
It is known that optical fibers must not be exposed to hydrogen because that gas degrades their transmission properties and possibly also their mechanical properties. The higher the partial pressure of hydrogen to which the fiber is subjected, the greater the degradation.
The hydrogen comes in particular from decomposition of the polymers constituting the coverings of the fibers or the material for assembling the fibers together into a ribbon. It can also come from decomposition of the filler material that is generally provided in the tube to hold the fibers in the tube and to prevent moisture from travelling in the event that the tube is punctured or degraded.
Such decomposition occurs naturally because of ageing.
When the tube is made of a plastics material, the permeability of the material enables hydrogen to be diffused. When the tube is made of metal or of some other non-porous material, hydrogen remains confined inside the tube, and the optical properties of the fibers are thus progressively degraded.
To solve that problem, one solution consists in using a tube made of stainless steel so as to avoid giving rise to hydrogen-generating corrosion, and in providing a filler material that has hydrogen-absorbent properties. For example, the filler material may be a polymer, in particular an unsaturated polymer with which a catalyst such as palladium is generally mixed.
Stainless steel and such a mixture of a polymer with a catalyst constitute materials that are costly.